cast5.cpp

vc环境下的pgp源码

/*____________________________________________________________________________
	Copyright (C) 1996-1999 Network Associates, Inc.
	All rights reserved.

	$Id: cast5.cpp,v 1.3 1999/03/10 02:31:42 heller Exp $
____________________________________________________________________________*/
#ifdef PGP_WIN32
#include "StdAfx.h"
#endif
#include <assert.h>
#include <string.h>
#include "cast5.h"
#include "cast5box.c"	/* S-box contents are defined in this file */

/* CAST is uniformly big-endian - byte access macros */
#define B0(x) ((x) >> 24 & 255)
#define B1(x) ((x) >> 16 & 255)
#define B2(x) ((x) >> 8 & 255)
#define B3(x) ((x) & 255)

/* Some macros used in the key scheduling code */
#define x0 B0(x0123)
#define x1 B1(x0123)
#define x2 B2(x0123)
#define x3 B3(x0123)
#define x4 B0(x4567)
#define x5 B1(x4567)
#define x6 B2(x4567)
#define x7 B3(x4567)
#define x8 B0(x89AB)
#define x9 B1(x89AB)
#define xA B2(x89AB)
#define xB B3(x89AB)
#define xC B0(xCDEF)
#define xD B1(xCDEF)
#define xE B2(xCDEF)
#define xF B3(xCDEF)
#define z0 B0(z0123)
#define z1 B1(z0123)
#define z2 B2(z0123)
#define z3 B3(z0123)
#define z4 B0(z4567)
#define z5 B1(z4567)
#define z6 B2(z4567)
#define z7 B3(z4567)
#define z8 B0(z89AB)
#define z9 B1(z89AB)
#define zA B2(z89AB)
#define zB B3(z89AB)
#define zC B0(zCDEF)
#define zD B1(zCDEF)
#define zE B2(zCDEF)
#define zF B3(zCDEF)

/*
 * This expands a 128-bit key to a 32-word scheduled key, where each round
 * uses two words: a 32-bit XOR mask and a 5-bit rotate amount.  Shorter keys
 * are just padded with zeros, and if they are 80 bits or less, the cipher
 * is reduced to 12 rounds (not implemented here).
 *
 * The feed-forward used with x0123 through yCDEF prevent any weak keys,
 * and the substitution to set up the xkey tables ensure that the subround
 * keys are not easily derivable from each other, so linear cryptanalysis
 * won't do very well against CAST.
 */
void
CAST5schedule(word32 xkey[32], byte const *k)
{
	word32 x0123, x4567, x89AB, xCDEF;
	word32 z0123, z4567, z89AB, zCDEF;
	int i;

	/* Initialize x0123456789ABCDEF with input key */
	x0123= (word32)k[ 0]<<24 | (word32)k[ 1]<<16 | (word32)k[ 2]<<8 | k[ 3];
	x4567= (word32)k[ 4]<<24 | (word32)k[ 5]<<16 | (word32)k[ 6]<<8 | k[ 7];
	x89AB= (word32)k[ 8]<<24 | (word32)k[ 9]<<16 | (word32)k[10]<<8 | k[11];
	xCDEF= (word32)k[12]<<24 | (word32)k[13]<<16 | (word32)k[14]<<8 | k[15];

	/* Now set up the key table */

	for (i = 0; i < 4; i++) {
		z0123 = x0123 ^ S5[xD] ^ S6[xF] ^ S7[xC] ^ S8[xE] ^ S7[x8];
		z4567 = x89AB ^ S5[z0] ^ S6[z2] ^ S7[z1] ^ S8[z3] ^ S8[xA];
		z89AB = xCDEF ^ S5[z7] ^ S6[z6] ^ S7[z5] ^ S8[z4] ^ S5[x9];
		zCDEF = x4567 ^ S5[zA] ^ S6[z9] ^ S7[zB] ^ S8[z8] ^ S6[xB];

		x0123 = z89AB ^ S5[z5] ^ S6[z7] ^ S7[z4] ^ S8[z6] ^ S7[z0];
		x4567 = z0123 ^ S5[x0] ^ S6[x2] ^ S7[x1] ^ S8[x3] ^ S8[z2];
		x89AB = z4567 ^ S5[x7] ^ S6[x6] ^ S7[x5] ^ S8[x4] ^ S5[z1];
		xCDEF = zCDEF ^ S5[xA] ^ S6[x9] ^ S7[xB] ^ S8[x8] ^ S6[z3];

		switch (i) {
		  case 0:
			/* Masking keys, rounds 0..7 */
			xkey[ 0] = S5[z8] ^ S6[z9] ^ S7[z7] ^ S8[z6] ^ S5[z2];
			xkey[ 2] = S5[zA] ^ S6[zB] ^ S7[z5] ^ S8[z4] ^ S6[z6];
			xkey[ 4] = S5[zC] ^ S6[zD] ^ S7[z3] ^ S8[z2] ^ S7[z9];
			xkey[ 6] = S5[zE] ^ S6[zF] ^ S7[z1] ^ S8[z0] ^ S8[zC];
			
			xkey[ 8] = S5[x3] ^ S6[x2] ^ S7[xC] ^ S8[xD] ^ S5[x8];
			xkey[10] = S5[x1] ^ S6[x0] ^ S7[xE] ^ S8[xF] ^ S6[xD];
			xkey[12] = S5[x7] ^ S6[x6] ^ S7[x8] ^ S8[x9] ^ S7[x3];
			xkey[14] = S5[x5] ^ S6[x4] ^ S7[xA] ^ S8[xB] ^ S8[x7];
			break;
		  case 1:
			/* Masking keys, rounds 8..15 */
			xkey[16] = S5[z3] ^ S6[z2] ^ S7[zC] ^ S8[zD] ^ S5[z9];
			xkey[18] = S5[z1] ^ S6[z0] ^ S7[zE] ^ S8[zF] ^ S6[zC];
			xkey[20] = S5[z7] ^ S6[z6] ^ S7[z8] ^ S8[z9] ^ S7[z2];
			xkey[22] = S5[z5] ^ S6[z4] ^ S7[zA] ^ S8[zB] ^ S8[z6];
			
			xkey[24] = S5[x8] ^ S6[x9] ^ S7[x7] ^ S8[x6] ^ S5[x3];
			xkey[26] = S5[xA] ^ S6[xB] ^ S7[x5] ^ S8[x4] ^ S6[x7];
			xkey[28] = S5[xC] ^ S6[xD] ^ S7[x3] ^ S8[x2] ^ S7[x8];
			xkey[30] = S5[xE] ^ S6[xF] ^ S7[x1] ^ S8[x0] ^ S8[xD];
			break;
		  case 2:
			/* Rotation keys, rounds 0..7 */
			xkey[ 1] = (S5[z8]^S6[z9]^S7[z7]^S8[z6]^S5[z2]) & 31;
			xkey[ 3] = (S5[zA]^S6[zB]^S7[z5]^S8[z4]^S6[z6]) & 31;
			xkey[ 5] = (S5[zC]^S6[zD]^S7[z3]^S8[z2]^S7[z9]) & 31;
			xkey[ 7] = (S5[zE]^S6[zF]^S7[z1]^S8[z0]^S8[zC]) & 31;
			
			xkey[ 9] = (S5[x3]^S6[x2]^S7[xC]^S8[xD]^S5[x8]) & 31;
			xkey[11] = (S5[x1]^S6[x0]^S7[xE]^S8[xF]^S6[xD]) & 31;
			xkey[13] = (S5[x7]^S6[x6]^S7[x8]^S8[x9]^S7[x3]) & 31;
			xkey[15] = (S5[x5]^S6[x4]^S7[xA]^S8[xB]^S8[x7]) & 31;
			break;
		  case 3:
			/* Rotation keys, rounds 8..15 */
			xkey[17] = (S5[z3]^S6[z2]^S7[zC]^S8[zD]^S5[z9]) & 31;
			xkey[19] = (S5[z1]^S6[z0]^S7[zE]^S8[zF]^S6[zC]) & 31;
			xkey[21] = (S5[z7]^S6[z6]^S7[z8]^S8[z9]^S7[z2]) & 31;
			xkey[23] = (S5[z5]^S6[z4]^S7[zA]^S8[zB]^S8[z6]) & 31;
		
			xkey[25] = (S5[x8]^S6[x9]^S7[x7]^S8[x6]^S5[x3]) & 31;
			xkey[27] = (S5[xA]^S6[xB]^S7[x5]^S8[x4]^S6[x7]) & 31;
			xkey[29] = (S5[xC]^S6[xD]^S7[x3]^S8[x2]^S7[x8]) & 31;
			xkey[31] = (S5[xE]^S6[xF]^S7[x1]^S8[x0]^S8[xD]) & 31;
			break;
		}
	}
	x0123 = x4567 = x89AB = xCDEF = 0;
	z0123 = z4567 = z89AB = zCDEF = 0;
}

#undef x0
#undef x1
#undef x2
#undef x3
#undef x4
#undef x5
#undef x6
#undef x7
#undef x8
#undef x9
#undef xA
#undef xB
#undef xC
#undef xD
#undef xE
#undef xF
#undef z0
#undef z1
#undef z2
#undef z3
#undef z4
#undef z5
#undef z6
#undef z7
#undef z8
#undef z9
#undef zA
#undef zB
#undef zC
#undef zD
#undef zE
#undef zF

/* Some macros used in the encryption/decryption code */
#define ROL(x,r) ((x)<<(r) | (x)>>(32-(r)))

#ifdef __GNUC__
#if __i386__
/* Redefine using GCC inline assembler */
#undef ROL
#define ROL(x,r) ({unsigned _y; __asm__("rol %%cl,%0" : "=g" (_y) : "0" (x), "c" (r)); _y;})
#endif /* __i386__ */
#endif /* __GNUC__ */

#define F1(x,xkey,i) (ROL((xkey)[2*(i)] + (x), (xkey)[2*(i)+1]))
#define F2(x,xkey,i) (ROL((xkey)[2*(i)] ^ (x), (xkey)[2*(i)+1]))
#define F3(x,xkey,i) (ROL((xkey)[2*(i)] - (x), (xkey)[2*(i)+1]))

#define G1(x) (((S1[B0(x)] ^ S2[B1(x)]) - S3[B2(x)]) + S4[B3(x)])
#define G2(x) (((S1[B0(x)] - S2[B1(x)]) + S3[B2(x)]) ^ S4[B3(x)])
#define G3(x) (((S1[B0(x)] + S2[B1(x)]) ^ S3[B2(x)]) - S4[B3(x)])

void
CAST5encrypt(byte const *in, byte *out, word32 const *xkey)
{
	word32 l, r, t;

	l = (word32)in[0]<<24 | (word32)in[1]<<16 | (word32)in[2]<<8 | in[3];
	r = (word32)in[4]<<24 | (word32)in[5]<<16 | (word32)in[6]<<8 | in[7];

	t = F1(r, xkey,  0); l ^= G1(t);
	t = F2(l, xkey,  1); r ^= G2(t);
	t = F3(r, xkey,  2); l ^= G3(t);
	t = F1(l, xkey,  3); r ^= G1(t);
	t = F2(r, xkey,  4); l ^= G2(t);
	t = F3(l, xkey,  5); r ^= G3(t);
	t = F1(r, xkey,  6); l ^= G1(t);
	t = F2(l, xkey,  7); r ^= G2(t);
	t = F3(r, xkey,  8); l ^= G3(t);
	t = F1(l, xkey,  9); r ^= G1(t);
	t = F2(r, xkey, 10); l ^= G2(t);
	t = F3(l, xkey, 11); r ^= G3(t);
	/* Stop here if only doing 12 rounds */
	t = F1(r, xkey, 12); l ^= G1(t);
	t = F2(l, xkey, 13); r ^= G2(t);
	t = F3(r, xkey, 14); l ^= G3(t);
	t = F1(l, xkey, 15); r ^= G1(t);

	out[0] = B0(r);
	out[1] = B1(r);
	out[2] = B2(r);
	out[3] = B3(r);
	out[4] = B0(l);
	out[5] = B1(l);
	out[6] = B2(l);
	out[7] = B3(l);
}

void
CAST5decrypt(byte const *in, byte *out, word32 const *xkey)
{
	word32 l, r, t;

	r = (word32)in[0]<<24 | (word32)in[1]<<16 | (word32)in[2]<<8 | in[3];
	l = (word32)in[4]<<24 | (word32)in[5]<<16 | (word32)in[6]<<8 | in[7];

	t = F1(l, xkey, 15); r ^= G1(t);
	t = F3(r, xkey, 14); l ^= G3(t);
	t = F2(l, xkey, 13); r ^= G2(t);
	t = F1(r, xkey, 12); l ^= G1(t);
	/* Start here if only doing 12 rounds */
	t = F3(l, xkey, 11); r ^= G3(t);
	t = F2(r, xkey, 10); l ^= G2(t);
	t = F1(l, xkey,  9); r ^= G1(t);
	t = F3(r, xkey,  8); l ^= G3(t);
	t = F2(l, xkey,  7); r ^= G2(t);
	t = F1(r, xkey,  6); l ^= G1(t);
	t = F3(l, xkey,  5); r ^= G3(t);
	t = F2(r, xkey,  4); l ^= G2(t);
	t = F1(l, xkey,  3); r ^= G1(t);
	t = F3(r, xkey,  2); l ^= G3(t);
	t = F2(l, xkey,  1); r ^= G2(t);
	t = F1(r, xkey,  0); l ^= G1(t);

	out[0] = B0(l);
	out[1] = B1(l);
	out[2] = B2(l);
	out[3] = B3(l);
	out[4] = B0(r);
	out[5] = B1(r);
	out[6] = B2(r);
	out[7] = B3(r);
}